1. Field of the Invention
The present invention relates in general to systems for transmitting document files between computers, and in particular to a document delivery system that provides a sender with verification that a receiver has successfully received and displayed a document.
2. Description of Related Art
U.S. Pat. No. 5,790,790 entitled “ELECTRONIC DOCUMENT DELIVERY SYSTEM IN WHICH NOTIFICATION OF SAID ELECTRONIC DOCUMENT IS SENT TO A RECIPIENT THEREOF”, issued Aug. 4, 1998 to Smith et al, describes a document delivery system in which a sender computer sends a file describing a document to a server computer. The server computer stores the document file at a network address and then sends an email notification to a receiver computer referencing the network address of the document file. The receiver computer can then use conventional file transfer protocol to download the document file from server computer. The receiver computer may then process the document file to produce a display of the document it describes. The server computer maintains a log indicting whether email was sent to the receiver and indicating whether the server forwarded the document to the receiver. The sender computer can access the log to determine whether the server computer forwarded the document file to the receiver computer.
In many applications it would be beneficial for a sender computer to be able to determine not only whether the server computer sent a document file to a receiver computer, but also whether the receiver computer actually received the document file and successfully displayed an image of the document it describes. A document file can be corrupted in transit between the sender computer and server computer or between the server computer and the receiver computer. Also although the receiver computer may receive an uncorrupted document file, software running on the receiver computer may be corrupted and unable to display the document.
What is needed is a document delivery system providing a means for enabling a sender computer transmitting a document file to a receiver computer via a server computer to determine whether the receiver computer has successfully received the document file and successfully displayed the document it represents.